/* Microsoft Reference Implementation for TPM 2.0
 *
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 *  included below. This software may be subject to other third party and
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 *  Copyright (c) Microsoft Corporation
 *
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 *
 *  BSD License
 *
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 *  are permitted provided that the following conditions are met:
 *
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 *  of conditions and the following disclaimer.
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 *  list of conditions and the following disclaimer in the documentation and/or
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 */
#include "Tpm.h"
#include "PolicyTemplate_fp.h"

#if CC_PolicyTemplate  // Conditional expansion of this file

/*(See part 3 specification)
// Add a cpHash restriction to the policyDigest
*/
//  Return Type: TPM_RC
//      TPM_RC_CPHASH           cpHash of 'policySession' has previously been set
//                              to a different value
//      TPM_RC_SIZE             'templateHash' is not the size of a digest produced
//                              by the hash algorithm associated with
//                              'policySession'
/*
tpm2_policytemplate(1) - Couples a policy with public template data digest of an object. 
This is a deferred assertion where the hash of the public template data of an object is 
checked against the one specified in the policy.
Tpm2 policytemplate (1)-将策略与对象的公共模板数据摘要耦合。这是一个延迟断言，
其中对象的公共模板数据的哈希值与策略中指定的哈希值进行了检查。

This command allows a policy to be bound to a specific creation template. This is most useful for an 
object creation command such as TPM2_Create(), TPM2_CreatePrimary(), or TPM2_CreateLoaded().
The templateHash parameter should contain the digest of the template that will be required for the 
inPublic parameter of an Object creation command.
If policySession→isTemplateHash is SET and policySession→cpHash is not equal to templateHash, the TPM 
shall return TPM_RC_VALUE.
NOTE 1 Revision 01.38 of this specification permitted the TPM to return TPM_RC_CPHASH.
Otherwise, if policySession→cpHash is already set, the TPM shall return TPM_RC_CPHASH.
NOTE 2 Revision 01.38 of this specification permitted the TPM to return TPM_RC_VALUE.
If the size of templateHash is not the size of policySession→policyDigest, the TPM shall return TPM_RC_SIZE. 
Otherwise, policySession→cpHash is set to templateHash.
NOTE 3 The digest calculation includes the TPM2B buffer but not the TPM2B size.

此命令允许将策略绑定到特定的创建模板。 这对于 TPM2_Create()、TPM2_CreatePrimary() 或 TPM2_CreateLoaded() 等对象创建命令最有用。
templateHash 参数应包含对象创建命令的 inPublic 参数所需的模板摘要。
如果 policySession→isTemplateHash 被设置并且 policySession→cpHash 不等于 templateHash，TPM 将返回 TPM_RC_VALUE。
注 1 本规范的修订版 01.38 允许 TPM 返回 TPM_RC_CPHASH。
否则，如果 policySession→cpHash 已经设置，TPM 将返回 TPM_RC_CPHASH。
注 2 本规范的修订版 01.38 允许 TPM 返回 TPM_RC_VALUE。
如果 templateHash 的大小不是 policySession→policyDigest 的大小，TPM 将返回 TPM_RC_SIZE。 否则，policySession→cpHash 被设置为 templateHash。
注 3 摘要计算包括 TPM2B 缓冲区但不包括 TPM2B 大小。

*/
TPM_RC
TPM2_PolicyTemplate(
    PolicyTemplate_In     *in             // IN: input parameter list
    )
{
    SESSION     *session;
    TPM_CC      commandCode = TPM_CC_PolicyTemplate;
    HASH_STATE  hashState;

// Input Validation

    // Get pointer to the session structure
    session = SessionGet(in->policySession);

    // If the template is set, make sure that it is the same as the input value
    // TODO: 这是什么场景会出现？
    if(session->attributes.isTemplateSet)
    {
        if(!MemoryEqual2B(&in->templateHash.b, &session->u1.cpHash.b))
            return TPM_RCS_VALUE + RC_PolicyTemplate_templateHash;
    }
    // error if cpHash contains something that is not a template
    else if(session->u1.templateHash.t.size != 0)
        return TPM_RC_CPHASH;

    // A valid templateHash must have the same size as session hash digest
    if(in->templateHash.t.size != CryptHashGetDigestSize(session->authHashAlg))
        return TPM_RCS_SIZE + RC_PolicyTemplate_templateHash;

// Internal Data Update
    // Update policy hash
    // policyDigestnew = hash(policyDigestold || TPM_CC_PolicyCpHash
    //  || cpHashA.buffer)
    //  Start hash
    CryptHashStart(&hashState, session->authHashAlg);

    //  add old digest
    CryptDigestUpdate2B(&hashState, &session->u2.policyDigest.b);

    //  add commandCode
    CryptDigestUpdateInt(&hashState, sizeof(TPM_CC), commandCode);

    //  add cpHashA
    CryptDigestUpdate2B(&hashState, &in->templateHash.b);

    //  complete the digest and get the results
    CryptHashEnd2B(&hashState, &session->u2.policyDigest.b);

    // update cpHash in session context
    session->u1.templateHash = in->templateHash;
    session->attributes.isTemplateSet = SET;

    return TPM_RC_SUCCESS;
}

#endif // CC_PolicyTemplateHash